Project Summary/Abstract Marijuana (cannabis sativa) is the most commonly used illicit substance by pregnant women in the US, with 1 in 12 pregnant women endorsing use and rates as high as 1 in 4 in poor, young, underserved mothers. With decreasing legal and medical sanctions, increasing availability, and increasing potency of US cannabis, there is high potential for increasing maternal use and fetal exposure. To our knowledge, there are currently no NIH-funded prospective human studies of prenatal cannabis use and offspring development or human studies of biological pathways linking prenatal cannabis and offspring development. We will conduct an intensive, prospective investigation of the specific effects of maternal prenatal cannabis use on infant neurobehavior including signs of withdrawal, infant stress response, and epigenetic regulation of endocannabinoid and glucocorticoid pathways. Central methodology involving prospective assessment of pregnant cannabis users (use ? 2X/week) and a tobacco-matched comparison group (n=125/group) across gestation followed by developmentally-sensitive measures of infant neurobehavior and stress response at 2 days, 1 and 6 months. An important innovation is our focus on epigenetic regulation of placenta endocannabinoid and glucocorticoid pathways as mediators of links between prenatal cannabis and infant neurobehavioral development. Our study also offers numerous innovations to ensure rigor, including one-on- one matching for tobacco use across cannabis and comparison groups, a propensity modeling approach to allow causal inference, exquisitely sensitive biomarkers and integrative classification of cannabis exposure, sophisticated, developmentally-sensitive measures of infant neurobehavior and stress response, and measurement of key alternative pathways. Our aims are: (1) to characterize effects of maternal cannabis use on infant neurobehavior including signs of withdrawal, (2) to characterize the impact of prenatal cannabis on infant glucocorticoid stress response over the first 6 months, (3) to characterize the impact of prenatal cannabis on epigenetic regulation of placenta glucocorticoid and endocannabinoid pathways, and (4) to test proposed placenta epigenetic pathways linking prenatal cannabis and infant neurobehavior. To our knowledge, the proposed study would be the first comprehensive investigation of the impact of prenatal cannabis use on infant neurobehavioral development as well as key plausible biological pathways. Our study is distinguished by its focus on a highly prevalent but understudied drug of abuse and innovative methods and novel biological pathways pioneered by our group. Results from the proposed study will provide critical data for obstetric providers and pregnant women, and will inform policy, regulations, and public health messaging regarding cannabis use by pregnant and reproductive age women. Results will also elucidate the earliest biomarkers of risk from prenatal cannabis exposure, with implications for identifying novel therapeutic targets to protect exposed offspring.